A program that grants points for using Bing search, which users can redeem for gift cards, sweepstakes entries, or charitable donations.
Same issue. Waiting does help because by then the receipts are either lost or thrown out. Sometimes for those that are worthy of keeping become too old to scan.
So I think this is a way for Microsoft reduce cost for themselves, by random issues that they are introducing themselves for plausible deniability. This goes hand in hand with random cool downs on counting points for searches. Their support say the same thing all the time - try again later, there is a cool down, etc etc. Basically non-action on their part.
I wouldn't be so pessimistic if it wasn't happening all the time.